The present invention relates to an input device based on an optical displacement system.
Optical technology is widely used in various consumer products. One such a product is an input device, e.g., a mouse, having an optical displacement system. The optical displacement system or optical module includes an optical sensor package, an LED, and a lens. The sensor package includes a sensor chip whereon electronic circuits are defined, a plurality of pins, and a package enclosing the chip.
The LED emits light that is scattered on an external surface and received by the sensor chip. The sensor chip uses the received images to determine the movement of the mouse. The movement of the mouse corresponds to the displacement information that is input to a host computer by the mouse. The displacement information is the displacement measured or detected by the mouse.
A mouse having such an optical displacement system is commonly referred to as an optical sensor mouse or optical mouse. The optical mouse is generally preferred over a mouse having a mechanical displacement system that uses a mechanical ball for obtaining displacement information. One reason is that the optical system generally only has solid state devices and does not have moveable parts, e.g., a displacement ball, that is more likely to breakdown from clogging or wear out. Another reason is that the optical system can be made to have a more compact size than a mechanical system, particularly with recent improvements in semiconductor fabrication technologies.
Reducing the size of the displacement system enables the mouse or input device to have a smaller form factor, thereby giving designers more freedom in adapting the internal structure of the product to the user requirements. In addition, a smaller-sized mouse provides easy portability and is desired by many consumers. Accordingly, although already small when compared to a mechanical displacement system, it would still be useful to reduce the size of an optical displacement system.